Catheter having closed loop array with in-plane linear electrode portion

ABSTRACT

A catheter adapted or high density mapping and/or ablation of tissue surface has a distal electrode array with offset spine loops, each spine loop having at least a pair of linear portions and a distal portion connecting the pair of linear portions, and one or more electrodes on each linear portion. The linear portions of the plurality of offset spine loops are arranged in-plane a single common plane, and the distal portions of the plurality of offset spine loops are arranged off-plane from the single common plane.

FIELD OF INVENTION

This invention relates to catheters, in particular, intravascularcatheters for tissue diagnostics and ablation.

BACKGROUND

Cardiac arrhythmia, such as atrial fibrillation, occurs when regions ofcardiac tissue abnormally conduct electric signals to adjacent tissue,thereby disrupting the normal cardiac cycle and causing asynchronousrhythm. Important sources of undesired signals are located in the tissueregion, for example, one of the atria or one of the ventricles.Regardless of the sources, unwanted signals are conducted elsewherethrough heart tissue where they can initiate or continue arrhythmia.

Procedures for treating arrhythmia include surgically disrupting theorigin of the signals causing the arrhythmia, as well as disrupting theconducting pathway for such signals. More recently, it has been foundthat by mapping the electrical properties of the endocardium and theheart volume, and selectively ablating cardiac tissue by application ofenergy, it is possible to cease or modify the propagation of unwantedelectrical signals from one portion of the heart to another. Theablation process destroys the unwanted electrical pathways by formationof non-conducting lesions.

In this two-step procedure-mapping followed by ablation-electricalactivity at points in the heart is typically sensed and measured byadvancing a catheter containing one or more electrical sensors into theheart, and acquiring data at a multiplicity of points. These data arethen utilized to select the target areas at which ablation is to beperformed.

For greater mapping resolution, it is desirable for a mapping catheterto provide very high density signal maps through the use of a multitudeof electrodes sensing electrical activity within a small area, forexample, about a square centimeter. For mapping within an atria or aventricle (for example, an apex of a ventricle), it is desirable for acatheter to collect larger amounts of data signals within shorter timespans. It is also desirable for such a catheter to be adaptable todifferent tissue surfaces, for example, flat, curved, irregular ornonplanar surface tissue, yet remain in a predetermined configurationwhere electrode spatial relationships are generally maintained duringsensing and mapping.

SUMMARY OF THE INVENTION

The catheter of the present invention is intended to enable high densitymapping and/or ablation of tissue surface, with a distal electrode arrayhaving a plurality of closed spine loops that are laterally offset fromeach other. Advantageously, the spine loops have electrode-carrying mainportions and distal connecting portions, where the electrode-carryingmain portions are arranged in a common plane (“in-plane”), with apredetermined configuration that is generally maintained by the distalconnecting portions which are off-plane and noninterfering with thein-plane arrangement of the electrode-carrying portions. The in-planearrangement of the spine loops maximizes electrode-to-tissue contact forhigh density mapping signals while the predetermined configurationprovides greater regularity, consistency and predictability in electrodeplacement on the tissue surface.

The predetermined configuration includes one or more spatialrelationships between adjacent spine loops and/or adjacent electrodes onadjacent spine loops. For example, the electrode-carrying main portionsof the spine loops may be linear and parallel to each other such that aconsistent spacing is provided and maintained between adjacentelectrodes during use of the catheter for electrophysiologic procedures,including, pacing, ECG reading, and the like).

In some embodiments, the catheter includes an elongated catheter bodyand a distal electrode array comprising a plurality of offset spineloops, with each spine loop having at least a pair of electrode-carryingportions and a distal portion connecting the pair of electrode-carryingportions, wherein the electrode-carrying portions of the offset spineloops are arranged in-plane in a single common plane, and the distalportions of the offset spine loops are arranged off-plane from thesingle common plane.

In some embodiments, the electrode-carrying portions of the offset spineloops are linear. The electrode-carrying portions of the offset spineloops may be parallel to each other. The distal portions may benonlinear, for example, curved or angularly shaped with corners.

In some embodiments, the offset configuration of the spine loopsincludes at least one electrode-carrying portion of each spine loopbeing positioned between electrode-carrying portions of one or moredifferent spine loops.

In some embodiments, the offset configuration of the spine loopsincludes the pair of electrode-carrying portions of each spine loopbeing separated therebetween by at least an electrode-carrying portionof a different spine loop.

In some embodiments, the distal portions of adjacent spine loops areangled oppositely off-plane from each other so as to remainnoninterfering with the in-plane arrangement of the electrode-carryingportions.

In additional embodiments, the catheter includes an elongated catheterbody, a distal electrode array comprising a plurality of offset spineloops, with each spine loop having at least a pair of linear portionsand a distal portion connecting the pair of linear portions, wherein thelinear portions of the offset spine loops are arranged in-plane in asingle common plane, and the distal portions of the plurality of offsetspine loops are arranged off-plane from the single common plane.

In some embodiments, the linear portions of the offset spine loops areparallel to each other and the distal portions are nonlinear.

In some embodiments, the offset arrangement of the spine loops includesat least one linear portion of each spine loop being positioned betweenlinear portions of one or more different spine loops.

In some embodiments, the offset arrangement of the spine loops includesthe pair of linear portions of each spine loop being separatedtherebetween by at least a linear portion of a different spine loop.

In some embodiments, the distal portions of adjacent spine loops areangled oppositely off-plane from each other.

A catheter of the present invention may also include one or more spacemembers extending between at least two adjacent linear portions to helpmaintain the predetermined configuration and/or spatial relationship(s).

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of a catheter of the present invention, inaccordance with some embodiments.

FIG. 2A is a side cross-sectional view of the catheter of FIG. 1,including a junction between a catheter body and a deflection section,taken along a first diameter.

FIG. 2B is a side cross-sectional view of the catheter of FIG. 1,including the junction of FIG. 2A, taken along a second diametergenerally perpendicular to the first diameter.

FIG. 2C is an end cross-sectional view of the deflection section ofFIGS. 2A and 2B, taken along line C-C.

FIG. 3A is a side cross-sectional view of the catheter of FIG. 1,including a junction between the deflection section and a distalelectrode assembly, taken along a first diameter.

FIG. 3B is a side cross-sectional view of the junction of FIG. 3A, takenalong a second diameter generally perpendicular to the first diameter.

FIG. 3C is an end cross-sectional view of the deflection section ofFIGS. 3A and 3B, taken along line C-C.

FIG. 3D is an end cross-sectional view of the junction of FIG. 3A, takenalong line D-D.

FIG. 4 is a perspective view of a junction between the deflectionsection and the distal electrode assembly of the catheter of FIG. 1,with parts broken away.

FIG. 5 is a perspective view of a distal electrode assembly of FIG. 1.

FIG. 5A is a side view of the distal electrode assembly of FIG. 5.

FIG. 5B is an end view of the distal electrode assembly of FIG. 5A,taken along line B-B.

FIG. 5C is an end view of a spine loop of FIG. 5A, taken along line C-C.

FIG. 6 is a detailed perspective view of an irrigated ring electrode ona spine loop, in accordance with some embodiments.

FIG. 6A is a side cross-sectional view of the irrigated ring electrodeof FIG. 6, taken along line A-A.

FIG. 6B is an end cross-sectional view of the irrigated ring electrodeof FIG. 6A, taken along line B-B.

FIG. 7 is partial perspective view of a distal electrode assembly, inaccordance with another embodiment.

FIG. 8 is a partial perspective view of a spine loop, in accordance withanother embodiment.

FIG. 9 is a partial perspective view of a spine loop, in accordance withanother embodiment.

FIG. 10 is a schematic drawing illustrating a method of using thecatheter of the present invention, according to one embodiment.

FIG. 11 is a schematic drawing illustrating a method of using thecatheter of the present invention, according to another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, the catheter 10 comprises an elongated catheter body12, an intermediate deflection section 14, a distal electrode assemblyor array 15, and a deflection control handle 16 attached to the proximalend of the catheter body 12. In accordance with a feature of the presentinvention, the distal electrode array 15 has a plurality of closedoffset spine loops 17 whose electrode-carrying portions lie within acommon plane.

With reference to FIGS. 2A and 2B, the catheter body 12 comprises anelongated tubular construction having a single, axial or central lumen18. The catheter body 12 is flexible, i.e., bendable, but substantiallynon-compressible along its length. The catheter body 12 can be of anysuitable construction and made of any suitable material. In someembodiments, the catheter body 12 comprises an outer wall 20 made ofpolyurethane or PEBAX. The outer wall 20 comprises an imbedded braidedmesh of stainless steel or the like to increase torsional stiffness ofthe catheter body 12 so that, when the control handle 16 is rotated, theintermediate section 14 of the catheter 10 rotates in a correspondingmanner.

The outer diameter of the catheter body 12 is not critical. Likewise,the thickness of the outer wall 20 is not critical, but is thin enoughso that the central lumen 18 can accommodate a puller wire, one or morelead wires, and any other desired wires, cables or tubes. If desired,the inner surface of the outer wall 20 is lined with a stiffening tube22 to provide improved torsional stability.

As shown in FIGS. 2A, 2B and 2C, the intermediate section 14 comprises ashorter section of tubing 19 having multiple lumens, for example, fouroff-axis lumens 31, 32, 33 and 34. The first lumen 31 carries aplurality of lead wires 40S for ring electrodes 37 carried on the spineloops 17. The second lumen 32 carries a first puller wire 24. The thirdlumen 33 carries a cable 36 for an electromagnetic position sensor 42and a plurality of lead wires 40D and 40P for distal and proximal ringelectrodes 38D and 38P carried on the catheter proximally of the distalelectrode array 15. The fourth lumen 34 (for example, diametricallyopposite of the second lumen 32 in the illustrated embodiment) carries asecond puller wire 26. The tubing 19 is made of a suitable non-toxicmaterial that is preferably more flexible than the catheter body 12. Onesuitable material for the tubing 19 is braided polyurethane, i.e.,polyurethane with an embedded mesh of braided stainless steel or thelike. The size of each lumen is not critical, but is sufficient to housethe lead wires, puller wires, the cable and any other components.

The useful length of the catheter, i.e., that portion that can beinserted into the body excluding the distal electrode array 15, can varyas desired. Preferably the useful length ranges from about 110 cm toabout 120 cm. The length of the intermediate section 14 is a relativelysmaller portion of the useful length, and preferably ranges from about3.5 cm to about 10 cm, more preferably from about 5 cm to about 6.5 cm.

A means for attaching the catheter body 12 to the intermediate section14 is illustrated in FIGS. 2A and 2B. The proximal end of theintermediate section 14 comprises an outer circumferential notch 27 thatreceives the inner surface of the catheter body 12. The intermediatesection 14 and catheter body 12 are attached by glue or the like.

If desired, a spacer (not shown) can be located within the catheter bodybetween the distal end of the stiffening tube (if provided) and theproximal end of the intermediate section. The spacer provides atransition in flexibility at the junction of the catheter body andintermediate section, which allows this junction to bend smoothlywithout folding or kinking. A catheter having such a spacer is describedin U.S. Pat. No. 5,964,757, the disclosure of which is incorporatedherein by reference.

As shown in FIGS. 3A and 3B, the distal electrode array 15 includes amounting stem 46 in the form of a short tubing mounted on a distal endof the tubing 19 of the intermediate deflection section 14. (In thatregard, it is understood that where the catheter 10 is without adeflection section 14, the mounting stem 46 is mounted on a distal endof the catheter body 12.) The stem 46 has a central lumen 48 to housevarious components. The intermediate section 14 and stem 46 are attachedby glue or the like. The stem 46 may be constructed of any suitablematerial, including nitinol.

As shown in FIG. 4, the stem 46 houses various components, including theelectromagnetic position sensor 42, and a distal anchor for the pullerwires 24 and 26. In the disclosed embodiment, the distal anchor includesone or more washers, for example, a distal washer 50D and a proximalwasher 50P, each of which has a plurality of matching axialthrough-holes that allow passage of components between the deflectionsection 14 and the stem 46 while maintaining axial alignment of thesecomponents relative to the longitudinal axis 95 of the catheter 10. Asalso shown in FIG. 3D, the through-holes include holes 54 and 56 thatare axially aligned with the second and fourth lumens 32 and 34 of thetubing 19, respectively, to receive a distal end of puller wires 24 and26, respectively. It is understood that the puller wires 24 and 26 mayform a single tensile member with a distal U-bend section that passesthrough the holes 54 and 56. With tension on the washers 50D and 50Pexerted by the U-bend section of the puller wires 24 and 26, the washersfirmly and fixedly abut against the distal end of the tubing 19 of thedeflection section 14 to distally anchor the U-bend section.

As also shown in FIG. 3D, each washer also includes through-hole 58which is axially aligned with the first lumen 31 and allows passage ofthe lead wires 40S from the deflection section 14 and into the lumen 48of the stem 46. Each washer further includes through-hole 57 which isaxially aligned with the third lumen 33 of the tubing 19 and allowspassage of the sensor cable 36 from the deflection section 14 into lumen48 of the stem 46 where the electromagnetic position sensor 42 ishoused. The lead wire 40D also passes through the hole 57 to enter thelumen 48 for attachment to the distal ring electrode 38D carried on theouter surface of the stem 46 via an opening (not shown) formed in theside wall of the stem 46 through which a distal end of the lead wire 40Dis welded or otherwise attached to the distal ring electrode 38D asknown in the art. Carried on the outer surface of the tubing 19 near thedistal end of the intermediate deflection section 14, a proximal ringelectrode 38P is connected to lead wire 40P via an opening 87 (FIG. 3B)formed in the side wall of the tubing 19 that provides communicationbetween the third lumen 33 and outside of the tubing 19. The distal endof the lead wire is welded or otherwise attached to the proximal ringelectrode 38P as known in the art.

Extending from the distal end of the stem 46 are the closed spine loops17 of the distal electrode array 15, as shown in FIG. 5. Each spine loophas a non-conductive covering 64 that extends the exposed length of eachspine loop. At the junction of distal electrode array 15 and the stem46, the non-conductive covering 64 of each spine may be sealed at itsproximal end to the stem 46 by the polyurethane 67 or the like.

In some embodiments, each spine loop 17 has a distal nonlinearconnecting portion 17D, a pair of linear main electrode-carryingportions 17L, and a pair of linear proximal support portions 17P thatconverge into the stem 46. As shown in FIG. 7, all linear main portions(e.g., 17L1, 17L2, 17L3 and 17L4) in the array 15 lie within a commonplane P (“in-plane”) so as to maximum electrode-to-tissue contact.Moreover, the linear main portions 17L are arranged in a predeterminedconfiguration within the common plane P, defined by one or morepredetermined spatial relationships with each other, as maintained bythe distal portions 17D of the loops which connect corresponding pairsof main portions 17L at their distal ends. In that regard, the distalportions 17D are angled out of the common plane P (“off-plane”) so thatthe distal portions 17D are free from contact with each other and arethus noninterfering with the linear main portions 17L remainingin-plane. The distal portions 17D are nonlinear, and may assume anycurved or angular shape, for example, triangular (FIG. 8) or rectangular(FIG. 9).

In the illustrated embodiment of FIG. 7, a first distal portion 17D1 isangled out of plane in one direction (e.g., upwardly) and a seconddistal portion 17D2 is angled out of plane in an opposite direction(e.g., downwardly). Furthermore, a third spine loop 17D3 is angled outof plane in the one direction (e.g., upwardly) and a fourth spine loop17D4 is angled out of plane in the opposite direction (e.g.,downwardly). As such, adjacent pair distal portions 17D1 and 17D2 areangled oppositely of each other, as well as adjacent pair distalportions 17D2 and 17D3, and similarly adjacent pair distal portions 17D3and 17D4. The off-plane angle θ may range between about 1 and 45 degreesfrom the common plane, and preferably between about 5 and 20 degrees,and more preferably be about 10 degrees.

Moreover, to maximize electrode density of the array 15 and efficiencyof each linear main portion 17L as an electrode-carrying portion, thespine loops 17 are in a laterally offset arrangement where at least onelinear main portion 17L of each spine loop is positioned between linearmain portions 17L of one or more different spine loop. Or, in otherwords, each pair of linear main portions 17L of a spine loop isseparated therebetweenby at least a linear main portion 17L of adifferent spine loop. As such, the array 15 is able to provide greaterelectrode density yet remain of a more simplistic construction where theelectrode-carrying linear main portions 17L of each spine loop extendin-plane as supported by the noninterfering distal portions 17D.

In the illustrated embodiment of FIG. 7, the spine loops are laterallyoffset. For example, at least one linear portion 17L1 is positionedbetween linear portions 17L2. Moreover, for example, the pair of linearportions 17L3 is separated therebetween by the linear portion 17L4.

Predetermined configuration within the common plane P may include one ormore predetermined spatial relationships between the spine loops orportions thereof. One or more spatial relationships may be defined byspacing S between adjacent linear main portions 17L along the length ofthe array, for example, proximal spacing SP and distal spacing SD, asshown in FIG. 5. Predetermined spatial relationships may also includepredetermined spacing d between the ring electrodes 37 carried on thelinear main portions 17L. In the illustrated embodiment of FIG. 5, thelinear main portions 17L are parallel with each other such that proximalspacings SPi and distal spacings SDi are equal between pairs of adjacentlinear main portions 17L. For example, where spacing SPi, SDi areuniform to each other and throughout the array 15, and spacing d isuniform throughout the array 15, the array 15 is configured to supportthe electrodes in a grid-like pattern, as shown in FIG. 5. It isunderstood that the spacings SPi and SDi may be varied throughout thearray, as desired or appropriate, to provide different configurations.

For anchoring a proximal end of the array 15 in the stem 46, theproximal portions 17P of the spine loops can be configured, as desiredor appropriate, to support the linear main portions 17L in-plane, forexample, in equi-angular distribution around a center of the stem. Inthe illustrated embodiment of FIG. 5, the four proximal portions 17P arepotted in four quadrants about the center longitudinal axis 46A of thestem 46.

The plurality of loops may range between about 2 and 4. Each spine loopmay have a exposed linear length ranging between about 5 and 50 mm,preferably about 10 and 35 mm, and more preferably about 28 mm. Thearray may have dimensions of about 1.5 cm×1.0 cm The spacing SP and SDbetween adjacent linear main portions 17L each may range between about 1mm and 20 mm, preferably about 2 and 10 mm, and more preferably about 4mm. The spacing d between electrodes ranges between about 0.5 mm-12 mm.The surface area of the array 15 may range between about 1.5 cm² to 3.0cm², preferably between about 1.9 cm² and 2.5 cm², and more preferablyabout 2.2 cm².

As shown in FIG. 4, each spine loop 17 has an elongated shape-memorysupport member 62 extending through the length of the loop. A proximalportion of each member 62 extends into a distal end portion of the stem46 and is anchored in the lumen 48 of the stem 46. Each spine loop 17has a nonconductive tubing or covering 64 that covers the shape-memorymember 62 and the plurality of ring electrode 37 carried on each linearmain portion 17L may range between about 6 and 12, preferably about 6and 9, and more preferably about 8. Accordingly, the distal electrodearray 15 carries a plurality of electrodes ranging between about 20 and72, preferably between about 28 and 36 electrodes, and more preferablyabout 32 electrodes. In some embodiments, the electrode density is about15 electrodes per square centimeter and dimensions of about 12 mm×18 mm.

The shape-support support member 62 is made of a material havingshape-memory, i.e., that can be temporarily straightened or bent out ofits original shape upon exertion of a force and is capable ofsubstantially returning to its original shape in the absence or removalof the force. One suitable material for the support member is anickel/titanium alloy. Such alloys typically comprise about 55% nickeland 45% titanium, but may comprise from about 54% to about 57% nickelwith the balance being titanium. A nickel/titanium alloy is nitinol,which has excellent shape memory, together with ductility, strength,corrosion resistance, electrical resistivity and temperature stability.The non-conductive covering 64 can be made of any suitable material, andis preferably made of a biocompatible plastic such as polyurethane orPEBAX. If desired, the support member 62 can be eliminated and thedistal end of the non-conductive covering 64 can be pre-formed to havethe desired curvature or configuration.

Each shape-memory support member 62 extending through its respectivenonconductive covering 64 has a proximal end that is received andanchored in the stem 46 by polyurethane 67 or the like. Lead wires 40Sfor the spine electrodes 37 extend through a protective polytube 68, asshown in FIG. 4. The lead wires 40S diverge at the distal end of thepolytube 68, and extend toward their respective shape-memory supportmember 62, into their respective nonconductive covering 64 of theirrespective spines. As shown in FIG. 5C, each lead wire 40S is connectedto its respective ring electrode 37 on the spine loop 17 via arespective opening 69 formed in the side wall of the covering 64 throughwhich a distal end of the lead wire reaches outside of the covering 64and is welded or otherwise attached to its ring electrode 37.

In other embodiments, irrigated ring electrodes 371 are carried on thespine loops 17, as shown in FIGS. 6, 6A and 6B. The spines forming theloops 17 include a multi-lumened tubing 80 having, for example, multiplelumens, including a first lumen 81 for the shape-memory member 62, asecond lumen 82 for lead wires 40S, and a third lumen 83 for passingirrigation fluid via a passage 88 formed in the sidewall of the tubing80 to annular space gap G between outer wall of the tubing 80 and sidewall of the ring electrode 371 which are formed with fluid ports 85. Afourth lumen 84 may be provided to pass cable 36D for distalelectromagnetic position sensor 42D (not shown).

The proximal ends of the lead wires 40S, 40D and 40P for the spine loopring electrodes 37 and for the distal and proximal ring electrodes 38Dand 38P, respectively, are electrically connected to a suitableconnector (not shown) in the distal end of the control handle 16, whichis connected to a source of ablation energy, e.g., RF energy, as isknown in the art. The lead wires 40S, 40D and 40P extend through thecentral lumen 18 of the catheter body 12 (FIG. 2B). The lead wires 40Sextend through the first lumen 31 of the tubing 19 of the intermediatesection 14, and the lead wires 40D and 40P extend through the thirdlumen 33 of the tubing 19 (FIGS. 2C and 3C). Passing through the holes58 in the washers 50D and 50P, the lead wires 40S extend through thepolytube 68 which protects them from being damaged by the hole 58 (FIGS.3D and 4).

In the depicted embodiment, the lead wires 40S extending through thecentral lumen 18 of the catheter body 12 and the first lumen 31 in thedeflection section 14 may be enclosed within a protective sheath 94 toprevent contact with other components in the catheter. The protectivesheath can be made of any suitable material, preferably polyimide. Aswould be recognized by one skilled in the art, the protective sheath canbe eliminated if desired.

The ring electrodes 37, 37I and 38D and 38P can be made of any suitablesolid conductive material, such as platinum or gold, preferably acombination of platinum and iridium, and mounted onto the non-conductivecover 64, the stem 46 and or the tubing 19 with glue or the like.Alternatively, the ring electrodes can be formed by coating thenon-conductive cover 64, the stem 46 and/or the tubing 19 with anelectrically conducting material, like platinum, gold and/or iridium.The coating can be applied using sputtering, ion beam deposition or anequivalent technique.

In some embodiments, each ring electrode is relatively short, having alength ranging from about 0.4 mm to about 0.75 mm. The electrodes mayalso be arranged in pairs, where two electrodes of a pair are spacedmore closely to each other than they are to other pairs of electrodes.The closely-spaced electrode pairs allow for more accurate detection ofnear field pulmonary vein potential versus far field atrial signals,which is very useful when trying to treat atrial fibrillation.Specifically, the near field pulmonary vein potentials are very smallsignals whereas the atria, located very close to the pulmonary vein,provides much larger signals. Accordingly, even when the mapping arrayis placed in the region of a pulmonary vein, it can be difficult for thephysician to determine whether the signal is a small, close potential(from the pulmonary vein) or a larger, farther potential (from theatria). Closely-spaced bipole electrodes permit the physician to moreaccurately determine whether he is looking at a close signal or a farsignal. Accordingly, by having closely-spaced electrodes, one is able totarget exactly the locations of myocardial tissue that have pulmonaryvein potentials and therefore allows the clinician to deliver therapy tothe specific tissue. Moreover, the closely-spaced electrodes allow thephysician to determine the exact anatomical location of the ostium/ostiaby the electrical signal.

In some embodiments, the proximal electromagnetic position sensor 42P ishoused in the lumen of the stem (FIG. 4). A sensor cable 36P extendsfrom a proximal end of the position sensor 42P, and through the hole 57of the washers 50 (FIG. 3D), the third lumen 33 of the tubing 19 of thedeflection section 14 (FIG. 2C), and the central lumen 18 of thecatheter body 12 (FIG. 2B). The cable 36P is attached to a PC board inthe control handle 16, as known in the art. In some embodiments, one ormore distal electromagnetic position sensors may be housed in the array,for example, in one or more distal portions of the array. Sensor cables36D may extend through the spine covering 64 (FIG. 5C) or the lumen 84of the tubing 80 (FIG. 6B).

As shown in FIGS. 2A and 2C, the puller wires 24 and 26 (whether as twoseparate tensile members or parts of a single tensile member) areprovided for bi-directional deflection of the intermediate section 14.The puller wires 24 and 26 are actuated by mechanisms in the controlhandle 16 that are responsive to a thumb control knob or a deflectioncontrol knob 11. Suitable control handles are disclosed in U.S. Pat.Nos. 6,123,699; 6,171,277; 6,183,435; 6,183,463; 6,198,974; 6,210,407and 6,267,746, the entire disclosures of which are incorporated hereinby reference.

The puller wires 24 and 26 extend through the central lumen 18 of thecatheter body 12 (FIG. 2A) and through the second and fourth lumens 32and 34, respectively, of the tubing 19 of the deflection section 14(FIG. 2C). As shown in FIGS. 3A and 3C, they extend through holes 54 and56, respectively of the washers 50. Where the puller wires are part of asingle tensile member, the single tensile member has a U-bend 24/26U(FIG. 3A) at the distal face of the distal washer 50D which anchors thedistal ends of the puller wires. In that regard, the U-bend extendsthrough a short protective tubing 70 to protect the puller wires fromthe holes 54 and 56. Alternatively, where the puller wires are separatetensile members, their distal ends may be anchored via T-bars, as knownin the art and described in, for example, U.S. Pat. No. 8,603,069, theentire content of which is incorporated herein by reference. In anycase, the puller wires 24 and 26 are made of any suitable metal, such asstainless steel or Nitinol, and each is preferably coated with TEFLON orthe like. The coating imparts lubricity to the puller wires. The pullerwires preferably have a diameter ranging from about 0.006 to about 0.010inch.

A compression coil 66 is situated within the central lumen 18 of thecatheter body 12 in surrounding relation to each puller wire 24, asshown in FIG. 2B. Each compression coil 66 extends from the proximal endof the catheter body 12 to the proximal end of the intermediate section14. The compression coils 66 are made of any suitable metal, preferablystainless steel. Each compression coil 66 is tightly wound on itself toprovide flexibility, i.e., bending, but to resist compression. The innerdiameter of the compression coil 66 is preferably slightly larger thanthe diameter of its puller wire. The Teflon coating on each puller wireallows it to slide freely within its compression coil.

The compression coil 66 is anchored at its proximal end to the outerwall 20 of the catheter body 12 by a proximal glue joint (not shown) andat its distal end to the intermediate section 14 by a distal glue joint92. Both glue joints may comprise polyurethane glue or the like. Theglue may be applied by means of a syringe or the like through a holemade the sidewalls of the catheter body 12 and the tubing 19. Such ahole may be formed, for example, by a needle or the like that puncturesthe sidewalls which are heated sufficiently to form a permanent hole.The glue is then introduced through the hole to the outer surface of thecompression coil 66 and wicks around the outer circumference to form aglue joint about the entire circumference of the compression coil.

Within the second and fourth lumens 32 and 34 of the intermediatesection 14, each puller wire 24 and 26 extends through a plastic,preferably Teflon, puller wire sheath 39 (FIGS. 2A and 2C), whichprevents the puller wires from cutting into the sidewall of the tubing19 of the deflection section 14 when the deflection section 14 isdeflected.

In use, a suitable guiding sheath (not shown) is inserted into thepatient with its distal end positioned at or near a desired tissuelocation for diagnostics such as mapping and/or treatment such asablation. An example of a suitable guiding sheath for use in connectionwith the present invention is the Preface Braided Guiding Sheath,commercially available from Biosense Webster, Inc. (Diamond Bar,Calif.). The catheter 10 is passed through the guiding sheath andadvanced therethrough to the desired tissue location. In particular, thespine loops 17 of the distal electrode array 15 fed into the proximalend of the guiding sheath. After the distal electrode array 15 hasreached the desired tissue location, the guiding sheath is pulledproximally, exposing at least the array. Outside of the guiding sheath36, the linear main portions 17L of the spine loops extend generally ina common plane, as shown in FIG. 5, as supported by the noninterferingangled distal portions 17D. The distal portions 17D connecting thelinear main portions 17L prevent the latter from spreading, divergingand/or going out of plane.

The array 15 has a first side and a second side. As shown in FIG. 10,the user places the first side against the tissue surface, with at leastthe intermediate section 14 (if not also a distal portion of thecatheter body 12) generally perpendicular to the tissue surface, andactuates the control handle to deflect the intermediate deflectionsection 14 (arrow D) such that the first side deflects toward thecatheter, which drags the first side of the linear main portions 17Lacross the tissue surface as the section 14 is deflecting. The linearmain portions 17L are dragged across the tissue surface while remaininggenerally parallel to each other (as maintained by the distal portions17D) along tracks T which are generally linear and parallel, and in thesame direction as the deflection direction D.

Alternatively, as shown in FIG. 11, the user actuates the control handleto deflect the section 14 along direction D with the first surface ofthe array 15 deflected toward the catheter. The user then positions atleast the distal portion of the catheter body 12 generally parallel withthe tissue surface and places the second surface of the array 15 againstthe tissue surface. The user then releases the deflection (alongopposite direction R) which drags the second surface of the linear mainportions 17L across the tissue surface as the deflection section 14straightens. The linear main portions 17L are dragged across the tissuesurface while remaining generally parallel to each other (as maintainedby the distal portions 17D) along tracks T which are generally linearand parallel, and in the direction R opposite to the deflectiondirection D.

In either manner, the spine electrodes 37 are carried in-plane on thelinear main portions 17L for maximizing contact with the tissue surfacewhile the linear main portions 17L generally maintain a consistentseparation spacing from each other as the spine loops are dragged acrossthe tissue surface for high density electrode sensing and uniform andpredictable mapping. By keeping the linear main portions 17L separated,they are less prone to overlap and the electrodes 37 are lesssusceptible to “cross talk” or electromagnetic interference that canarise when two electrodes are in overly close proximity or contact. Inaccordance with a feature of the invention, the array has an “n x m”electrode layout or arrangement, for example, four spines, with eightelectrodes on each spine, for a total of 32 closely-spaced ringelectrodes 37 for mapping.

In some embodiments, the distal electrode array 15 includes a spacermember 86, e.g., a bar or bracket that extends between at least twospines to mechanically restrain them and keep them in a predeterminedspatial relationship. The spacer member can be configured to restrainmovement in one or more directions while allowing movement in otherdirections. In the illustrated embodiment of FIG. 5, the spacer member86 extends between linear portions 17L, fixed at their ends to thelinear portions 17L by adhesive, e.g. polyurethane, although it isunderstand that the spacer member may extend between any two or more ofthe same and/or different portions of the spine loops 17, as desired orappropriate. Regions of the spine loops may also be heat bonded ormelted together as desired or appropriate.

In some embodiments, the ring electrodes 38D and 38P proximal of thearray 15 serve as reference electrodes for visualization of the catheteron a 3-D mapping system, such as CARTO.RTM 3 SYSTEM available fromBiosense Webster, Inc., which automatically locates the EM sensor 42,processes reference location values from electrodes 38D and 38P, whichare at a constant location from the EM sensor(s) and determines thelocation of the electrodes 37 and 37I and visualizes the remainder ofthe electrode array 15.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. As understood by one of ordinary skill in the art, thedrawings are not necessarily to scale. Also, different features ofdifferent embodiments may be combined as needed or appropriate.Moreover, the catheters described herein may be configured to applyvarious energy forms, including microwave, laser, RF and/or cryogens.Accordingly, the foregoing description should not be read as pertainingonly to the precise structures described and illustrated in theaccompanying drawings, but rather should be read consistent with and assupport to the following claims which are to have their fullest and fairscope.

What is claimed is:
 1. A catheter comprising: an elongated catheterbody; and a distal electrode array comprising a plurality of offsetspine loops, each spine loop having at least a pair ofelectrode-carrying portions and a distal portion connecting the pair ofelectrode-carrying portions, wherein the electrode-carrying portions ofthe plurality of offset spine loops are arranged in-plane a singlecommon plane, and the distal portions of the plurality of offset spineloops are arranged off-plane from the single common plane.
 2. Thecatheter of claim 1, wherein the electrode-carrying portions of theplurality of offset spine loops are linear.
 3. The catheter of claim 2,wherein the electrode-carrying portions of the plurality of offset spineloops are parallel to each other.
 4. The catheter of claim 1, whereinthe distal portions are nonlinear.
 5. The catheter of claim 1, whereinat least one electrode-carrying portion of each spine loop is positionedbetween electrode-carrying portions of one or more different spineloops.
 6. The catheter of claim 1, wherein the pair ofelectrode-carrying portions of each spine loop are separatedtherebetween by at least a electrode-carrying portion of a differentspine loop.
 7. The catheter of claim 1, wherein distal portions ofadjacent spine loops are angled oppositely off-plane from each other. 8.The catheter of claim 1, wherein each electrode-carrying portionincludes one or more ring electrodes.
 9. The catheter of claim 8,wherein the ring electrodes include irrigated ring electrodes.
 10. Acatheter comprising: an elongated catheter body; a distal electrodearray comprising a plurality of offset spine loops, each spine loophaving at least a pair of linear portions and a distal portionconnecting the pair of linear portions, and one or more electrodes oneach linear portion, wherein the linear portions of the plurality ofoffset spine loops are arranged in-plane a single common plane, and thedistal portions of the plurality of offset spine loops are arrangedoff-plane from the single common plane.
 11. The catheter of claim 10,wherein the linear portions of the plurality of offset spine loops areparallel to each other.
 12. The catheter of claim 10, wherein the distalportions are nonlinear.
 13. The catheter of claim 10, wherein at leastone linear portion of each spine loop is positioned between linearportions of one or more different spine loops.
 14. The catheter of claim10, wherein the pair of linear portions of each spine loop are separatedtherebetween by at least a linear portion of a different spine loop. 15.The catheter of claim 10, wherein distal portions of adjacent spineloops are angled oppositely off-plane from each other.
 16. The catheterof claim 10, wherein the one or more ring electrodes include irrigatedring electrodes.
 17. The catheter of claim 10, further comprising one ormore space members extending between at least two adjacent linearportions.
 18. The catheter of claim 10, wherein the plurality of offsetspine loops ranges between about two and four.
 19. The catheter of claim10, wherein each spine loop includes an elongated shape memory member.20. A catheter comprising: an elongated catheter body; a distalelectrode array comprising a plurality of offset spine loops, each spineloop having at least a pair of linear portions, one or more electrodeson each linear portion, and one or more space members extending betweenat least two adjacent linear portions, wherein the linear portions ofthe plurality of offset spine loops are arranged in-plane a singlecommon plane, and the distal portions of the plurality of offset spineloops are arranged off-plane from the single common plane.